nondisjunction

This term is a highly specialized technical descriptor used almost exclusively within the fields of genetics, cytology, and medicine. It describes a specific mechanical failure during meiosis or mitosis, carrying a neutral, clinical tone. It is not used in casual conversation or as a metaphor for general failure or separation.

Because it refers to a specific biological event or process, it is typically treated as an uncountable noun in scientific literature. While one might refer to "instances of nondisjunction," the word itself describes the phenomenon rather than a discrete object that is counted.